# checkstr = input('请输入要判断的字符串：\n')
# flag = True
# low = 0
# high = len(checkstr) - 1
# while low < high:
#     if checkstr[low] != checkstr[high]:
#         flag = False
#         break
#     low += 1
#     high -= 1
# if flag:
#     print('"{}"是回文串。'.format(checkstr))
# else:
#     print('"{}"不是回文串。'.format(checkstr))



# strs = 'Rain falls    on field and tree.'
# print(strs)
# split_strs = strs.split()
# print(split_strs)
# join_strs = ''.join(split_strs)
# print(join_strs)